Accelerating and improving the consistency of rapid-acting analog insulin absorption and action for both subcutaneous injection and continuous subcutaneous infusion using recombinant human hyaluronidase

Insulin pumps in children - a systematic review

BACKGROUND

Insulin pump therapy is a real breakthrough in managing diabetes Mellitus, particularly in children. It can deliver a tiny amount of insulin and decreases the need for frequent needle injections. It also helps to maintain adequate and optimal glycemic control to reduce the risk of metabolic derangements in different tissues. Children are suitable candidates for pump therapy as they need a more freestyle and proper metabolic control to ensure adequate growth and development. Therefore, children and their caregivers should have proper education and training and understand the proper use of insulin pumps to achieve successful pump therapy. The pump therapy continuously improves to enhance its performance and increase its simulation of the human pancreas. Nonetheless, there is yet a long way to reach the desired goal.

AIM

To review discusses the history of pump development, its indications, types, proper use, special conditions that may enface the children and their families while using the pump, its general care, and its advantages and disadvantages.

METHODS

We conducted comprehensive literature searches of electronic databases until June 30, 2022, related to pump therapy in children and published in the English language.

RESULTS

We included 118 articles concerned with insulin pumps, 61 were reviews, systemic reviews, and meta-analyses, 47 were primary research studies with strong design, and ten were guidelines.

CONCLUSION

The insulin pump provides fewer needles and can provide very tiny insulin doses, a convenient and more flexible way to modify the needed insulin physiologically, like the human pancreas, and can offer adequate and optimal glycemic control to reduce the risk of metabolic derangements in different tissues.

Safety of recombinant human hyaluronidase PH20 for subcutaneous drug delivery

INTRODUCTION

The glycosaminoglycan hyaluronan forms a gel-like substance, which presents a barrier to bulk fluid flow in the subcutaneous (SC) space, limiting SC drug delivery volume and administration rates. Recombinant human hyaluronidase PH20 (rHuPH20) acts locally to temporarily remove this barrier, facilitating rapid SC delivery of large volumes and/or high doses of sequentially or co-administered therapeutics.

AREAS COVERED

An extensive clinical and post-marketing dataset of safety and immunogenicity of rHuPH20 in its current applications with approved therapeutics demonstrates that rHuPH20 acts locally, without measurable systemic absorption at the SC doses used in the approved products, and is well tolerated in combination with several co-administered therapeutic agents across diverse patient groups. The immunogenicity profile demonstrates no adverse effects associated with treatment-emergent rHuPH20 antibody responses. Immunogenicity to monoclonal antibodies co-formulated with rHuPH20 shows no clinical difference between SC and intravenous administration. Safety assessments of patient subsets for special populations, including children, elderly patients, and pregnant women, raise no additional safety concerns.

EXPERT OPINION

The benefits of SC administration for patients and healthcare systems often outweigh those of intravenous administration, driving future initiation of SC-only drug development programs. Injection devices allowing large-volume SC administration could be facilitated by incorporating co-formulated biologics containing rHuPH20.

Recombinant human hyaluronidase PH20-mediated dermal spreading activity in mice is not altered by steroids, antihistamines, or salicylic acid

OBJECTIVES

Drug-drug interaction studies for hyaluronidase safety assessments have evaluated only animal-derived enzyme preparations. We therefore set out to evaluate whether high-dose administration of two antihistamines, a potent corticosteroid, steroid hormone, adrenocorticotropic hormone (ACTH), or salicylic acid would alter the dispersive activity of recombinant human hyaluronidase PH20 (rHuPH20).

METHODS

NCr nu/nu mice were pretreated with diphenhydramine, cetirizine, dexamethasone, estrogen, ACTH, salicylic acid, and/or neutral-buffered saline (NBS). An hour following final pretreatment, dosed mice were anesthetized with ketamine/xylazine and placed in an imaging chamber. A 120 mg/mL immunoglobulin G (IgG) solution with 0.3 μg/mL IgGDL755 (labeled IgG) was injected intradermally, with/without 2,000 U/mL rHuPH20. Fluorescent images of labeled IgG dispersion were acquired ≤20 min post injection.

RESULTS

Dispersion of high-concentration labeled IgG combined with rHuPH20 was greater at all time points vs. antibody alone. At 20 min post injection (last time point), the antibody dispersion area was significantly increased with rHuPH20 vs. without rHuPH20 (p≤0.005). The relative percent increase in antibody dispersion with rHuPH20 ranged from 22.8‒106.6% over the 20-min time course, compared with the corresponding non-rHuPH20 treated groups. The area of labeled IgG dispersion was statistically similar between rHuPH20 groups pretreated with an active compound and their paired NBS pretreated controls.

CONCLUSIONS

The addition of 2,000 U/mL rHuPH20 to a high-concentration antibody solution reproducibly incre-ased local antibody dispersion. Systemic pretreatment with diphenhydramine, cetirizine, dexamethasone, estrogen, ACTH, or salicylic acid did not affect the enzymatic spreading activity of rHuPH20, as measured by intradermal dispersion of labeled IgG in mice.

Recombinant Human PH20: Baseline Analysis of the Reactive Antibody Prevalence in the General Population Using Healthy Subjects

Background

Recombinant human PH20 (rHuPH20) is used to depolymerize hyaluronan in the subcutaneous space, increasing the dispersion and absorption of co-administered drugs. While ~ 5 to 10% of rHuPH20 treatment-naïve healthy volunteers have demonstrated rHuPH20-reactive antibodies, associations with age, sex, fertility, and immune disorders remain unknown.

Objectives

Using demographically diverse healthy volunteers, we assessed the prevalence of rHuPH20-reactive antibodies in the general population and potential associations with fertility and autoimmunity diseases.

Methods

In total, 896 subjects aged ≥ 12 years (767 adults; 129 children) without prior exposure to rHuPH20 were enrolled. A demographic and limited medical history review was performed, and K3-EDTA-anticoagulated plasma was analyzed for rHuPH20-reactive antibodies using a bridging immunoassay.

Results

Adult and pediatric positivity rates for rHuPH20-reactive antibodies were 5.2% (40/767) and 1.6% (2/129), respectively. Titers ranged from 5 to 2560 (median 30). In five antibody-positive subjects from whom repeated samples were available, antibody titers remained unchanged or decreased fourfold over periods up to 590 days. The prevalence of rHuPH20-reactive antibodies significantly increased with age (p = 0.0006) and was significantly higher in males than in females (p = 0.0010). Men who had fathered children had a significantly increased prevalence of rHuPH20-reactive antibodies than men who had not (p = 0.0036), whereas the rate of childbearing was not significantly different between rHuPH20 antibody-positive and -negative women. The prevalence between racial/ethnic groups was not significantly different, nor was the presence/absence of an autoimmune disorder.

Conclusions

Approximately 1/20 of the adult population had rHuPH20-reactive antibodies. The reason remains unknown; however, no evidence for a negative effect on fertility or association with autoimmune disease was demonstrated.

Electronic supplementary material

The online version of this article (10.1007/s40259-018-0260-y) contains supplementary material, which is available to authorized users.

Can Hyaluronidase Be an Alternative Postoperative Anti-edema Agent to Dexamethasone? Preliminary Results of an Animal Study

PURPOSE

Recombinant human hyaluronidase (rHuPH20) is widely used as a spreading factor, which enhances the absorption of subcutaneously injected medicines. The anti-inflammatory and anti-edema effects of the enzyme were demonstrated in previous studies. In the present study, the anti-edema effect of rHuPH20 was compared with that of dexamethasone in a traumatic rat paw edema model.

MATERIALS AND METHODS

Twenty-four Sprague-Dawley rats (weight 200 to 450 g) were divided into 3 groups: control (group 1), rHuPH20 (group 2), and dexamethasone (group 3). Traumatic edema was induced in the right hind paws of the rats using Feeney's weight-drop model. After edema induction, 0.4 mL of rHuPH20 (100 U/kg = 0.88 μg/kg dose) and 0.4 mL of dexamethasone (0.5 mg/kg dose) were injected into the right hind paws of the rats in groups 2 and 3. The paw volumes were measured before edema induction and at 3, 6, 12, 24, 48, and 72 hours after induction using a plethysmometer. The Mann-Whitney U test was used for the statistical analyses. Probabilities < .05 were accepted as statistically significant.

RESULTS

The between percentage change in the edema mean values of groups 1 and 3 showed no significant difference at all time points; however, group 2 showed significantly less change in the edema mean values at 3, 6, 12, 24, and 48 hours after edema induction (P < .05) compared with group 1. The change in the edema mean value for group 2 was significantly less than that for group 3 at 3, 6, 12, 24, and 48 hours after edema induction (P < .05).

CONCLUSIONS

Local rHuPH20 injection more effectively reduced the edema that was induced traumatically in rat paws than did dexamethasone. However, further clinical studies are needed regarding the use of rHuPH20 as a postoperative anti-edema agent in place of dexamethasone.

Duration of Catheter Use in Patients with Diabetes Using Continuous Subcutaneous Insulin Infusion: A Review

Increasing proportions of patients with diabetes use continuous subcutaneous insulin infusion (CSII) therapy mostly due to its clinical efficacy and flexibility for insulin dosing and adjustments. Some challenges are nevertheless associated with this technology. A key and underlooked component of CSII technical difficulties is the subcutaneous catheter used to infuse insulin. Several adverse events (AEs) have been experienced by patients in relation to catheters, such as blockage, kinking, and insertion site reactions, including irritation, infections, lipohypertrophies etc., all of which could compromise the metabolic control. With the objective of minimizing these AEs, recommendations for changing catheters every 2-3 days have historically been provided by manufacturers based on reports derived from small studies and anecdotal data. The aim of this review was to provide an updated analysis of current recommendations and patients' practices in relation to frequency of catheter change. Our main findings are: (1) adequately designed and powered studies investigating optimal catheter wearing time are still lacking; (2) increasing catheter wearing time is generally associated with increased frequency of catheter AEs; (3) however, interpatient variability is large, with some individuals needing to change their catheters every 2-3 days, whereas others probably being able to keep them in place for longer periods without problems. Further research is thus warranted to provide more solid and evidence-based recommendations while exploring personalized approaches at the same time. Increasing catheter wear life without significant side effects is an important goal to simplify CSII therapy and reduce its associated costs and burdens.

Challenges and Opportunities for the Subcutaneous Delivery of Therapeutic Proteins

Biotherapeutics is a rapidly growing drug class, and over 200 biotherapeutics have already obtained approval, with about 50 of these being approved in 2015 and 2016 alone. Several hundred protein therapeutic products are still in the pipeline, including interesting new approaches to treatment. Owing to patients' convenience of at home administration and reduced number of hospital visits as well as the reduction in treatment costs, subcutaneous (SC) administration of biologics is of increasing interest. Although several avenues for treatment using biotherapeutics are being explored, there is still a sufficient gap in knowledge regarding the interplay of formulation conditions, immunogenicity, and pharmacokinetics (PK) of the absorption of these compounds when they are given SC. This review seeks to highlight the major concerns and important factors governing this route of administration and suggest a holistic approach for effective SC delivery.

Pharmacotherapy of type 2 diabetes: An update

Type 2 diabetes (T2DM) is a leading cause of morbidity and mortality worldwide and a major economic burden. The prevalence of T2DM is rising, suggesting more effective prevention and treatment strategies are necessary. The aim of this narrative review is to summarize the pharmacologic treatment options available for patients with T2DM. Each therapeutic class is presented in detail, outlining medication effects, side effects, glycemic control, effect on weight, indications and contraindications, and use in selected populations (heart failure, renal insufficiency, obesity and the elderly). We also present representative cost for each antidiabetic category. Then, we provide an individualized guide for initiation and intensification of treatment and discuss the considerations and rationale for an individualized glycemic goal.

Insulin analogues in type 1 diabetes mellitus: getting better all the time

The treatment of type 1 diabetes mellitus consists of external replacement of the functions of β cells in an attempt to achieve blood levels of glucose as close to the normal range as possible. This approach means that glucose sensing needs to be replaced and levels of insulin need to mimic physiological insulin-action profiles, including basal coverage and changes around meals. Training and educating patients are crucial for the achievement of good glycaemic control, but having insulin preparations with action profiles that provide stable basal insulin coverage and appropriate mealtime insulin peaks helps people with type 1 diabetes mellitus to live active lives without sacrificing tight glycaemic control. Insulin analogues enable patients to achieve this goal, as some have fast action profiles, and some have very slow action profiles, which gives people with type 1 diabetes mellitus the tools to achieve dynamic insulin-action profiles that enable tight glycaemic control with a risk of hypoglycaemia that is lower than that with human short-acting and long-acting insulins. This Review discusses the established and novel insulin analogues that are used to treat patients with type 1 diabetes mellitus and provides insights into the future development of insulin analogues.

[Fast-acting insulin - new developments towards more flexibility for the patient]

BACKGROUND

Post-prandial insulin secretion occurs under physiological conditions very fast and in adequate concentrations. This mechanism is impaired in patients with type 2 diabetes and severe increases of postprandial glucose levels may occur. In order to achieve physiological conditions and to avoid postprandial hyperglycemia, exogenous insulin and insulin analogues should be absorbed very fast and appropriate maximum concentrations should be reached very quickly.

METHOD

Overview RESULTS AND CONCLUSIONS: The development of new bolus insulins is focused on improved pharmacokinetic and pharmacodynamic properties. Not only new pharmaceutical formulations, but also different application sites and systems have been investigated. The latest innovations resulted in even faster acting insulins, which may offer patients improved postprandial glucose control and greater flexibility regarding meal planning.

Continuous subcutaneous insulin infusion therapy and multiple daily insulin injections in type 1 diabetes mellitus: a comparative overview and future horizons

INTRODUCTION

Continuous subcutaneous insulin infusion (CSII) therapy is currently accepted as a treatment strategy for type 1 diabetes. Transition from multiple daily injection therapy (MDI; including basal-bolus regimens) to CSII is based on expectations of better metabolic control and fewer hypoglycaemic events. Evidence to date has not been always conclusive.

AREAS COVERED

Evidence for CSII and MDI in terms of glycaemic control, hypoglycaemia and psychosocial outcomes is reviewed in the adult and paediatric population with type 1 diabetes. Findings from studies on threshold-based insulin pump suspension and predictive low glucose management (PLGM) are outlined. Limitations of current CSII application and future technological developments are discussed.

EXPERT OPINION

Glycaemic control and quality of life (QOL) may be improved by CSII compared to MDI depending on baseline HbA1c and hypoglycaemia rates. Future studies are expected to provide evidence on clinical and cost effectiveness in those who will benefit the most. Training, structured education and support are important to benefit from CSII. Novel technological approaches linking continuous glucose monitoring (CGM) and CSII may help mitigate against frequent hypoglycaemia in those at risk. Development of glucose-responsive automated closed-loop insulin delivery systems may reduce the burden of disease management and improve outcomes in type 1 diabetes.

Faster-acting insulin aspart: earlier onset of appearance and greater early pharmacokinetic and pharmacodynamic effects than insulin aspart

AIMS

To evaluate the pharmacokinetics and pharmacodynamics of faster-acting insulin aspart and insulin aspart in a randomized, single-centre, double-blind study.

METHODS

Fifty-two patients with type 1 diabetes (mean age 40.3 years) received faster-acting insulin aspart, insulin aspart, or another faster aspart formulation (not selected for further development), each as a single 0.2 U/kg subcutaneous dose, under glucose-clamp conditions, in a three-way crossover design (3-12 days washout between dosing).

RESULTS

Faster-acting insulin aspart had a faster onset of exposure compared with insulin aspart, shown by a 57% earlier onset of appearance [4.9 vs 11.2 min; ratio 0.43, 95% confidence interval (CI) 0.36; 0.51], a 35% earlier time to reach 50% maximum concentration (20.7 vs 31.6 min; ratio 0.65, 95% CI 0.59; 0.72) and a greater early exposure within 90 min after dosing. The greatest difference occurred during the first 15 min, when area under the serum insulin aspart curve was 4.5-fold greater with faster-acting insulin aspart than with insulin aspart. Both treatments had a similar time to maximum concentration, total exposure and maximum concentration. Faster-acting insulin aspart had a significantly greater glucose-lowering effect within 90 min after dosing [largest difference: area under the curve for the glucose infusion rate (AUC(GIR), 0-30 min) ratio 1.48, 95% CI 1.13; 2.02] and 17% earlier time to reach 50% maximum glucose infusion rate (38.3 vs 46.1 min; ratio 0.83, 95% CI 0.73; 0.94). The primary endpoint (AUC(GIR, 0-2 h)) was 10% greater for faster-acting insulin aspart, but did not reach statistical significance (ratio 1.10, 95% CI 1.00; 1.22). Both treatments had similar total and maximum glucose-lowering effects, indicating similar overall potency.

CONCLUSIONS

Faster-acting insulin aspart was found to have earlier onset and higher early exposure than insulin aspart, and a greater early glucose-lowering effect, with similar potency.

Subcutaneous fluid and drug delivery: safe, efficient and inexpensive

Patients with difficult venous access or oral intolerance and clinical situations with inadequate response to oral therapy have generated the need for alternative routes of delivery for drugs and fluids.

The purpose of this study was to conduct a systematic review examining the evidence for subcutaneous (SC) administration of drugs and/or fluids.

We used a broad search strategy using electronic databases CINAHL, EMBASE, PubMed and Cochrane library, key terms and ‘Medical Subject Headings’ (MeSH) such as ‘subcutaneous route’, ‘hypodermoclysis’ and the name/group of the most used drugs via this route (e.g. ‘ketorolac, morphine, ceftriaxone’, ‘analgesics, opioids, antibiotics’).

We conclude that the SC route is an effective alternative for rehydration in patients with mild–moderate dehydration and offers a number of potential advantages in appropriately selected scenarios. Experience of administering drugs by this route suggests that it is well tolerated and is associated with minimal side-effects.

Human immunoglobulin 10 % with recombinant human hyaluronidase: replacement therapy in patients with primary immunodeficiency disorders

Human immunoglobulin is an established replacement therapy for patients with primary immunodeficiency disorders (PIDs). Recombinant human hyaluronidase (rHuPH20) is a spreading factor that temporarily digests hyaluronan in the skin interstitium enabling large volumes of fluid or drug solutions to be infused and absorbed subcutaneously. HyQvia® (IGHy) is a new combination product whereby rHuPH20 is injected subcutaneously, followed by human immunoglobulin 10 % infused through the same needle. Thus, IGHy can be administered at a reduced frequency compared with non-facilitated subcutaneous injection of human immunoglobulin, and with a lower frequency of infusion reactions than with intravenous administration. Home-based administration of IGHy is also feasible for adequately trained patients. IGHy was compared with intravenous human immunoglobulin 10 % in a non-randomized, open-label, phase 3 study in patients aged ≥2 years with PIDs who were receiving human immunoglobulin replacement therapy (n = 87). In this study, trough IgG concentrations, acute serious bacterial infection rates (primary endpoint) and occurrences of adverse events during the IGHy treatment period were generally similar to those observed during an intravenous treatment period. IGHy was associated with a numerically lower rate of systemic adverse events and a numerically higher rate of localized adverse events than those observed with intravenous treatment. Compared with intravenous administration, IGHy was administered at a significantly higher maximum flow rate and at a similar frequency. Most patients preferred IGHy over intravenous administration. IGHy offers a new method for subcutaneous delivery of human immunoglobulin replacement therapy in patients with PIDs.

Improved Postprandial Glucose Control Using the InsuPad Device in Insulin-Treated Type 2 Diabetes: Injection Site Warming to Improve Glycemic Control

BACKGROUND

Delays in the time-action profiles of premeal boluses of rapid-acting insulin analogs contribute to early postmeal hyperglycemia in patients with diabetes. We tested whether applying local heat to skin around the injection site to increase the rate of insulin absorption reduces postprandial hyperglycemia in patients with type 2 diabetes.

METHODS

Fourteen patients with type 2 diabetes (4 females; age 61.6 ± 8.4 years, HbA1c 8.42 ± 1.13%; BMI 29.10 ± 5.61 kg/m(2)) on intensified insulin therapy underwent 5-hour meal tolerance tests (MTTs) with a standardized liquid meal after an overnight fast on 2 study days. Subjects injected 0.2 U/kg of insulin aspart or lispro subcutaneously into the abdominal skin on both days with and without the use of the InsuPad device.

RESULTS

Following the premeal bolus injection of rapid-acting insulin analog, infusion site warming led to a rise in plasma insulin levels to peak concentrations that were significantly earlier than without skin warming (mean ± SD 52 ± 26.7 vs 80 ± 51.3 minutes, P < .005) as well as increase in plasma insulin levels during the first hour after injection (mean ± SD 63.5 ± 32.7 IU vs 48.0 ± 25.0 uU.min/ml, P = .019). As a result, the area under the curve of the postprandial glucose excursion during the first 2 hours (the primary study outcome) and the entire 5 hours after the meal were significantly reduced (P = .007 and P = .03, respectively) with skin warming around the injection site.

DISCUSSION AND CONCLUSIONS

Use of the InsuPad to increase the rate of insulin absorption provides an effective means to achieve better control of postmeal glucose excursions in type 2 diabetic patients receiving premeal injections of rapid-acting insulin analogs.

Overview of recombinant human hyaluronidase-facilitated subcutaneous infusion of IgG in primary immunodeficiencies

Subcutaneous administration of immunoglobulin (IGSC) in a home setting, compared with intravenous administration, can improve patient quality of life. During IGSC, however, the subcutaneous extracellular matrix inhibits flow and fluid entry into the vascular compartment, which limits the amount of drug delivered. Recombinant human hyaluronidase (rHuPH20) increases the absorption and dispersion of infused fluids and drugs. Results from a Phase III, prospective, open-label, noncontrolled study of patients with primary immunodeficiencies indicated that IGSC infusion, facilitated by rHuPH20, is well tolerated and delivers infusion volumes at treatment intervals and rates equivalent to intravenous administration. This drug evaluation provides an overview of rHuPH20 and results of clinical studies of IGSC infusion facilitated by rHuPH20 in patients with primary immunodeficiencies.

Subcutaneous versus intravenous administration of rituximab: pharmacokinetics, CD20 target coverage and B-cell depletion in cynomolgus monkeys

The CD20-specific monoclonal antibody rituximab (MabThera^®, Rituxan^®) is widely used as the backbone of treatment for patients with hematologic disorders. Intravenous administration of rituximab is associated with infusion times of 4–6 hours, and can be associated with infusion-related reactions. Subcutaneous administration of rituximab may reduce this and facilitate administration without infusion-related reactions. We sought to determine the feasibility of achieving equivalent efficacy (measured by endogenous B-cell depletion) and long-term durability of CD20 target coverage for subcutaneously administered rituximab compared with intravenous dosing. In these preclinical studies, male cynomolgus monkeys were treated with either intravenous rituximab or novel subcutaneous formulation of rituximab containing human recombinant DNA-derived hyaluronidase enzyme. Peripheral blood samples were analyzed for serum rituximab concentrations, peripheral B-cell depletion, and CD20 target coverage, including subset analysis according to CD21+ status. Distal lymph node B-cell depletion and CD20 target coverage were also measured. Initial peak serum concentrations of rituximab were significantly higher following intravenous administration than subcutaneous. However, the mean serum rituximab trough concentrations were comparable at 2 and 7 days post-first dose and 9 and 14 days post-second dose. Efficacy of B-cell depletion in both peripheral blood and distal lymph nodes was comparable for both methods. In lymph nodes, 9 days after the second dose with subcutaneous and intravenous rituximab, B-cell levels were decreased by 57% and 42% respectively. Similarly, levels of peripheral blood B cells were depleted by >94% for both subcutaneous and intravenous dosing at all time points. Long-term recovery of free unbound surface CD20 levels was similar, and the duration of B-cell depletion was equally sustained over 2 months for both methods. These results demonstrate that, despite initial peak serum drug level differences, subcutaneous rituximab has similar durability, pharmacodynamics, and efficacy compared with intravenous rituximab.

Patch pump versus conventional pump: postprandial glycemic excursions and the influence of wear time

BACKGROUND AND AIMS

The aim of this study was to compare blood glucose and plasma insulin profiles after bolus insulin infusion by a patch pump (PP) versus a conventional pump (CP), directly after placement and after Day 3 of use.

PATIENTS AND METHODS

Twenty patients with type 1 diabetes came in for two blocks of visits: one block of two visits while wearing the OmniPod® (Insulet Corp., Bedford, MA) insulin pump (PP) and one block of two visits while wearing the Medtronic Diabetes (Northridge, CA) Paradigm® pump (CP). Patients administered an identical mealtime insulin bolus of at least 6 IU.

RESULTS

For PP, maximum glucose levels were 28.7% lower on Day 3 (P=0.020), when maximum insulin levels were 30.3% higher (P=0.002). For CP, maximum glucose levels were 26.5% lower on Day 3 (P=0.015), when maximum insulin levels were 46.4% higher (P=0.003). Glucose levels (mean [interquartile range]) were significantly lower on Day 3 for PP (168.2 [145.8] mg/dL vs. 139.4 [77.8] mg/dL; P=0.013), but not significantly so for CP (159.0 [66.1] mg/dL vs. 139.5 [57.9] mg/dL; P=0.084). Mean insulin levels were significantly higher on Day 3 for CP (195 [120] pmol/L vs. 230 [90] pmol/L; P=0.01), but not significantly so for PP (178 [106] pmol/L vs. 194 [120] pmol/L; P=0.099). There were no significant differences between the two catheter lengths.

CONCLUSIONS

Postprandial glycemic excursions were lower on Day 3 of catheter wear time, but there were no differences between PPs and CPs. These findings support the proposal that catheter wear time plays an important role in insulin absorption.

Ultrafast-acting insulins: state of the art

Optimal coverage of prandial insulin requirements remains an elusive goal. The invention of rapid-acting insulin analogs (RAIAs) was a big step forward in reducing postprandial glycemic excursions in patients with diabetes in comparison with using regular human insulin; however, even with these, the physiological situation cannot be adequately mimicked. Developing ultrafast-acting insulins (UFIs)-showing an even more rapid onset of action and a shorter duration of action after subcutaneous (SC) administration-is another step forward in achieving this goal. The need for UFIs has been gradually recognized over the years, and subsequently, a number of different approaches to cover this need are in clinical development. A rapid increase in circulating insulin levels can be achieved by different measures: modification of the primary structure of insulin molecule (as we know from RAIAs), addition of excipients that enhance the appearance in the monomeric state post-injection, or addition of enzymes that enable more free spreading of the insulin molecules in the SC tissue. Other measures to increase the insulin absorption rate increase the local blood flow nearby the insulin depot in the SC tissue, injecting the insulin intradermally or applying via another route, e.g., the lung. The development of these approaches is in different stages, from quite early stages to nearing market authorization. In time, daily practice will show if the introduction of UFIs will fulfill their clinical promise. In this review, the basic idea for UFIs will be presented and the different approaches will be briefly characterized.